Walter Mildew is Arthur and Lucy's father. Mr Mildew is an inventor, and he spends all his time crashing about in his chaotic little study, trying to invent things. Most of his inventions don’t work, which is why the family is so hard-up. But Mr Mildew is such an absent-minded father that he hardly seems to notice that his cottage is falling down. Arthur and Lucy’s mother died a long time ago, so he is in charge of all the house-keeping – but he is so forgetful that he can never remember which meal is which. So as often as not the children find themselves eating tinned spaghetti for breakfast, and porridge for supper.
Appearance: Mr Mildew is the scruffiest of all the Mildews. He never brushes his hair, and he always wears the same purple smoking jacket, which is falling to bits.
Likes: His own inventions. His favourite invention of all was his automatic grape-peeler, which was sold by a department store in London and made him quite rich for a short time.
Dislikes: His latest invention, which is causing him a terrible headache. He is trying to create a battery-operated mouse that gobbles the crumbs off a dinner-table, like a Hoover. It is called "The Hungry House Mouse" - but there is something wrong with its digestive system, and no sooner has it gobbled the crumbs up than it sicks them out again.